An active layer of the light-emitting diode is between two different conductivity cladding layers. When a current is applied to the electrodes above the two cladding layers, the electrons and the holes from the two cladding layers can inject into the active layer, are combined to generate the omnidirectional light in the active layer that is emitted from every surfaces of the light emitting diode. Due to its different mechanism from the incandescent lamp, the light emitting diode is called the cold light source. A light emitting diode is applied widely in different fields such as automobiles, computers, communications, and consumption electronic products because it has low volume, long life-time, low driving voltage, low consumption electric quantity, rapid response speed, and good shock-proof advantages.
Nevertheless, the application of the conventional light emitting diode has a restriction for it can only be operated under the direct current with low voltage. The high voltage or alternating current might damage the light emitting diode easily, so it needs a converter system to be adopted in the city electricity system. Furthermore, during a conventional light emitting diode assembly process, there is usually an electric static discharge that increase the instantaneous reversion voltage, and then make the light emitting diode breakdown.